1. Field of the Invention
The present invention relates to a window guide structure, or sash such as in an automobile door for any type of sliding window. More particularly, in the present invention the sash guides movement of the window, including the ascent and descent of the window, in the main body of the door or any other location of a window so that the window can slide along the sash.
2. Description of the Related Art
As shown in FIG. 14, sashes 103 are respectively provided at front and rear positions of door panel 101 of an automobile. Each of the sashes 103 is interposed between the inner and outer panels of the main body of the door panel 101. The sashes 103 guide the front and rear ends of a door window 102 when the door window 102 ascends or descends. These sashes 103 are disposed below the belt line of the door and are referred to as lower sashes. Following the glass run of the upper portion of the door panel 101, the lower sashes guide the front and rear ends of the window 102 when the window 102 is opened or closed.
Metal sashes have hitherto been employed and a glass run has been mounted on the metal sash. Sashes made of synthetic resin consisting of polyamide or polyacetal also have recently been employed to reduce the weight of the automobile and reduce costs.
For sashes made of synthetic resin, in order to omit the glass run, ensure the sliding property of the ascending or descending window 102, and prevent rattling of the window 102, protrusions 104 are provided, as shown in FIG. 15. The protrusions 104 extend from inner opposing surfaces 131 of the sash 103 and have U-shaped cross-sections. The protrusions 104 are positioned in opposing relationship at the opposing surfaces 131 (see FIG. 15), or can be positioned in alternating relationship in the longitudinal direction of the sash 103, as disclosed in Japanese Utility Model Unexamined Publication No. 59-102867. However, because synthetic resin is greater in thermal expansion and shrinkage than metal, there is the need to provide sufficient space between the window surface and the protrusion 104, and consequently, rattling of the window 102 cannot be prevented sufficiently.
The lower sash according to prior art has a guide portion such as the one shown in a perspective view in FIG. 16. The guide portion 100 of this lower sash is provided with a resin base 112 and a plurality of guide pieces 114 extending outwardly from the resin base 112. The guide pieces 114 are spaced in two rows by a distance slightly wider than the thickness of the window 102, and the window 102 slides between the spaced guide pieces 114.
In the above guide portion 100, however, vibration of the window 102, such as when travelling on a rough road, sometimes causes striking sounds to occur between the window 100 and the guide pieces 114. Also, sliding of the window 102 along the guide pieces 114 also sometimes produces sounds between the window 102 and the guide pieces 114.
Another conventional lower sash is disclosed in Japanese Patent Unexamined Publication No. 7-257510. FIG. 17 is a perspective view showing this lower sash 120. The lower sash 120 is provided with a metallic lower sash main body 122 in the form of a U-shaped cross-section and lip portions 124 mounted on the top ends of the sidewalls 122a of the lower sash main body 122. The lip portions 124 are formed over the overall length of the main body 122 of the lower sash. The lip portions 124 are bonded to the main body 122 by using an adhesive or are fixed by a clamp. In this lower sash 120 the window 102 slides between both lip portions 124.
In the lower sash 120, however, because the main body 122 thereof is formed of metal material, the attachment of the lip portions 124 to the main body 122 must be performed with an adhesive or the like and therefore the operation is troublesome. In addition, there has been the demand for reducing the quantity of material, such as rubber or resin, in the lip portions 124 themselves to reduce production cost.